1. Field of the Invention
The invention relates to a process for reconditioning of standardized tight head drums of plastic which are made in one piece by blow molding or which consist of a blow-molded drum body with welded, injection-molded upper drum head, for re-use as tight head drums or for use as wide-neck drums, the reconditioned tight head and wide-neck drums having the same nominal volume and the same height and diameter dimensions according to DIN standard.
Strict legal environmental protection regulations require the transition from disposable to re-usable packing drums such as plastic or steel drums and conversion to packing drums with larger volume with the objective of reducing residual amounts and developing new re-usable packing drums which can be reconditioned with respect to relieving the environment of harmful materials and which can be easily cleaned and from which all residues can be optimally removed for reconditioning and for proper disposal by destruction without pollutants, for example, by burning or for reprocessing of the production material.
2. Description of Related Art
The development of reconditionable hard packing drums which are easy to dispose of and which are protected against contamination by pollutants, essentially steel and plastic drums, led to generic tight head drums and for example tight head drums with removable cover known from DE 35 39 656 A1 which in part replace the closed tight head drums used to date. These drums are provided as required with a flexible inside covering called the inliner or a bag of plastic film, for example, polyethylene film, or of a diffusion-proof coextruded metal-plastic composite foil, for example an aluminum foil covered on both sides with polyethylene. Drums with an inliner are known for example from DE 88 10 760 U1. Inliners are used in plastic and steel drums when they are filled with products which are difficult to dispose of, such as dispersions, for example, dyes, which can hardly be removed from the drum wall after drying. Inliners of a diffusion-proof composite foil in plastic drums suppress diffusion of solvent-containing contents into the drum wall and possible rediffusion of solvents from the drum wall. In steel drums the inliner saves the inside coating previously necessary to protect the steel sheet against corrosive media and corrosion.
From DE 42 42 370 C1 a process is known for reconditioning of tight head drums with a blow-molded wide-neck drum body with a drum border and injection-molded tight head cover welded onto the drum border with a flange for re-use as a closed tight-head drum or for re-use as a wide-neck drum with removable cover.
The necking-in of the wide-neck drum body used for a tight head drum with a nominal volume of for example 220 liters in the neck area which is necessary for an arrangement of the drum border within the outline of the drum body compared to a tight head drum with the same nominal volume according to DIN 6131 with a drum body which is roughly continuously cylindrical and which has the same diameter as the wide-neck drum body results in a larger drum height compared to the standardized tight-head drum to obtain a nominal volume of 220 liters.
These different drum heights result in the disadvantage that mixed stacking of tight head drums with a wide-neck drum body and a welded-on tight head cover as well as of wide neck drums with a removable cover according to DE 42 42 370 C1 and of tight head drums blown in one piece according to DIN 6131 for transport by means of standardized containers and for storage purposes is impossible.